Conventionally, grinding chips resulting from grinding become spongy bodies that contain a grinding fluid, such as grinding water and grinding oil used during grinding, and after dried in a machining plant, the spongy bodies, are incinerated in an incineration furnace, disposed by landfill for value, or used as a reducing agent for blast furnaces in a steelworks.
For grinding chips containing about 70% of ferrous metals, for example, as described in the Japanese Patent Laid-Open No. 56-23237, a treatment method of briquetting is known so that such grinding chips are reused as a raw material in blast furnaces of a steelworks. In this method, grinding chips, turning chips and metal powders for composition adjustment are blended and heated in a primary heating furnace to remove moisture, oil and the like, whereby a preliminary briquette is made, and after that, briquetting is performed by secondary heating in a high-temperature secondary heating furnace.
Furthermore, as described in the Japanese Patent Laid-Open No. 2002-241854, there is known a method of making a briquette by which grinding chips resulting from grinding are naturally dried to reduce the content of a grinding fluid to not more than 20 wt %, shot waste resulting from shot blasting and gear cutting chips resulting from gear cutting, the oil content of which is reduced to not more than 6 wt %, are added to these grinding chips, the blending ratio of these materials is adjusted to 2 (grinding chips): 1 (shot waste): 7 (gear cutting chips), and a pressing pressure is applied after mixing and string.
However, in the method described in the Japanese Patent Laid Open No. 56-23237, equipment and devices such as a large heating furnace must be provided on a large scale and besides the treatment requires a large quantity of energy, posing the problem that the effect of recycling resources decreases by half.
The briquette making method described in the Japanese Patent Laid-Open No. 2002-241854, which involves mixing shot waste, has the problem that during the extrusion of moisture by applying a pressing force, shot waste becomes a hindrance and that in some ways of mixing, shot waste induces a decrease in shatter strength and variations in required strength after briquetting, thereby causing cracks.
The present invention was made in view of these problems in conventional techniques and has as its object the provision of a briquette meeting required strength that is formed in an energy-saving manner from ferrous metal machining scrap, such as grinding chips, a method of making the briquette, a mashing crusher of grinding chips capable of reducing the energy consumed in briquetting in order to effectively reuse grinding chips, and a briquette making apparatus that uses the mashing crusher.